Luminous discharge device



E April 2J, M LUMINOUS DISCHARGE DEVICE `Fileci Feb. 25. 1929 INVENToR:

Patented Apr. 25, 1933 UNITED STATES PATENT OFFICE MONTFOB MORRISON, FMONTCLAIR, NEW JERSEY, ASSIGNOR, BY MESNE ASSIGN- MENTS, 'l

WESTINGHOUSE LAMP COMPANY, A CORPORATION OF PENNSYLVANIA v.LUMINoUspIscHARGE nnvrcr.` Aiipuuon mea February 25, 1929. serial No.342,463.

The present invention relates to luminous ,discharge tubes of thegaseous ionization Y trode seals which are shielded rom positivevertising signs and the like. This invention is constituted of some ofthe elements disclosed in my Patent No. 1,842,6241ssued J anuary 26,1932, and is in part a part thereof'.

Among the objects of my invention are; to provide electrodes which havesurface characteristics which eliminate excessive electrostatic fieldconcentration about the discharge surface of the electrodes; to provideelectrodes which operate at a. lower temperature by providing doolingfor the electrodes 1n direct 'contact with the surrounding alr; toprovide for the reduction of electrode vaporization and sputterlng; torovlde elecionization bombardment under operation, to provide electrodeswhich are fixed in firm contact with the walls of the discharge tube; toprovide an electrode which can be transported with substantially nostraln upon the seal, and to provide electrodes adapted to be held in ayreceptacle.

Further and other objects will be pointed out and obvious upon readingthe speclication, but' the novel features of my mvention are moreparticularly set forth 1n the claims. The gure represents one embod1mentof my invention, partly in elevation and partly` in section, togetherwith a dlagrammatlc drawing of one of the clrcults I use 1n theemployment of my invention.

In the prior art it has been customary 1n making luminous dischargetubes to provide a long restricted tubing with bulbous glass ends inwhich said bulbous ends are provided internal electrodes. Internale1ectrodes have serious disadvantages, among which is the inability ofthe electrode to radiate the heat generated in it advantageously and asa result of which the electrode not only gives off gas during operationbut further vaporizes some of its constltuted elements both of which arevery detrimental to .the operation of the tube.

trode which is. external of the en d of the restricted tubing andthereby I not only remove a great many mechanical limitations, but bringthe electrode itself into direct contact with the air which provides anydegree of cooling desired.' In some cases I may provide heat radiatorsattached to the electrode used in my invention to further reduce theoperating temperature of the electrode.

The present invention is particularly ldifferentiated from those of theprior art by the electrode being external of the glass tube, the ends ofwhich tubing are open. The invention is further differentiated fromthose of the prior art in that the electrode is in firm contact with thewalls of the tube itself, and the electrode proper may be sealeddirectly to the wall of the glass tube.

This structure further provides for the making of strong mechanicaljoints t0- gether With Well supported structures which greatly contrastsitself with the fragile devices of the prior art.

My electrode construction further provides, by the employment ofelectrostatic Field distribution accomplished by the shaping of theelectrodes, a novel means of utilizing electrostatic surfacecharacteristics, more fully disclosed in my prior application abovereferredto, in such a Way as to direct considerable of the discharge andmetallic vapors away from the glass Walls of the tube and therebytending to make this said vaporized metal condense on the electrodeitself'.

The present invention further provides for the constructing ofindividual letters and installing them by the simple process ofinserting the electrodes into proper receptacles. If and when burn-outsoccur, highly skilled labor is not required to removel or Areplace partsas the operation is more simple than removing or replacing ordinaryincandescent lamp bulbs.

Referring to the figure, 1 is a translucent tube which may be bent intoany shape as indicated in the figure at 28, and may be provided with anexpanded portion 2 having a conical surface 3 and extended portion 4.One form of my electrode proper is shown at which has the form of athmbie with a closed end 6 and a recessed annular groove 7 to rest uponthe extended portion 4 and a flared conical surface 8 adapted to fit theconical surface 3 of the tube 1.

In practice the main body of my electrode 5 may be made of.l anysuitable material, one example of which is copper, and the translucenttube at 2 may be made of any suitable material such as glass, forinstance that known to thel trade as 702-P. By proper preparation,heating and manipulation the glass and copper may besealed at point 3 byone skilled in the art to which my invention appertains.

In some cases I may make the entire tubing 1 of the same glass or I mayuse a different material or glass for the restricted portion of thetubing 1 and seal it either directly to the material at the expandedportion 2 or include in between these tWo materials a third materialmore suitable to be fused to both. For instance, if it is made of glassknown to the trade as Pyrex, I can' with some difiicultyseal thisdirectly to the 7 (l2-P at 2, but in most cases I prefer to use a stepof glass in between the two known to the trade as Uranium glass. ThisUranium glass seals more readily to both Pyrex and to 702-15 than does702-P seal directly to Pyrex.

The depressed annular groove 7 serves to hold the major portion of theelectrode 5 away from the glass extension 4, and it serves to preventthe heat from the electrode 5 under operation from cracking the glass 4fI have discovered that in the construction of my electrodes in somecases there seems to be a considerable advantage in employing a materialfor the discharge surface of my electrode, which material in some casesis not easily formed into the desired electrode shape and further, inmany cases the material most desirable for the electrode dischargesurface is too expensive for the application; in addition to which inmany cases the desired discharge surface materials lacks severalphysical characteristics to make it desirable for use as an electrodebody.

^ In desirable cases I prefer to coat my electrode with a more suitablematerial for the electric dischargel surface than that out of which thebody of the electrode is made and in which case I provide a coatingindicated at 27. This coating may be of any suitable material whateverprovided it reduces sputtering and/or vaporization ofthe electrodesurface.

One suitable material I find to be thorium and this may be depositedupon the discharge surface of the electrode by any means whatever, forinstance by the method disclosed in my Patent No. 1,506,852 issuedSeptember 2, 1924, though I do not limit'myself advantageous toelectroplate a desirable coating upon the electrode and use a differentmaterial such as, for instance, cadmium.l

rality of heat radiators 9 to further cool the electrode andto divertthe heat from the clecltrode away froln the glass and the glass sea 12is a modified electrode in which 22 is an ellipsoidal enlargement ofthe` cylindrical surface 23. The electrode 12 has a cylindrical glassprojection 24, similar to that in electrode 5, being sealed at 25similar tothe seal 3, and having ka generally fiat' surface 26, beingfinor near the plane of the cylindrical end of the projection 24.

'By a theorem in electrostatics relating to the distribution ofelectrostatic fields from surfaces, as more fully discussed in one of myprior above referred to applications,.-

the electrical discharge from the surface within the bulbous )ortion 22is substantially orthogonal to the discharge surface in the immediateneighborhood thereof, and, therefore, the discharge from the inner wallof this electrode is largely away from the actual wall of the glass andtends to combine in suchl a Way as to largely concentrate itself withinthe general center of the projection 24.

Apparently in such discharge devices, vaporized particles seem to movesomewhat in a straight line from the surface from which they originate,and seem not to be influenced at least totally by the electrostaticfield distribution. It will be observed from' consideration of theinterior contour of .the hollow ellipsoid 22 that very few particlesorig inating from the internal electrostatic surface of this electrodewill strike the glass Walls of the tube, at least a very smallpercentage as compared with the internal electrodes of the prior art.Electr0de12 may be further provided with heat radiators 26,

the same purpose as those provided for electrode of the construction 5.

I further rovidereceptacles 10 and 11 which are a apted to receive theelectrodes 5 and 12. With this construction it will be appreciated lthatthe entire luminous dis-l charge device can be removed from thereceptacle or lugged into it without the aid to this process. In somecases it may be'of skilled la r, the complete luminous dis- In somecases I desire to provide a plu- .80

lus

charge device being removed from the rece l y tacles by pulling thedevice away from t e receptacles along the axis of the electrodes. 13 isan alternating current generator which by means of leads 14 and 15,through switch 16, supplies primary 17 of transformer 18 withalternating current energy. Secondary 19 provides alternating currentexcitation for receptacles 10 and 11 through leads 2O and 21. In thisway the receptacles 10 and 11, and hence electrodes 5 and 12, areprovided with alternating current energy.

In constructing a completed tube, ordinarily I provide the tube 1 withtwo electrodes, as illustrated by 5 or 12, the tubing being gas-tightand the whole device prepared, degasified, evacuated and filled with anydeslred gas and sealed off of the pumps, as is well understood by thoseSkilled in the art to which my invention appertains.

In the operation of my device, it will be appreciated that substantiallyall of the discharge from electrodes 5 and l2 comes from those portionsbeyond the extensions 4 and 24. The discharge passes from electrode 5through the tubing 1, and thence to electrode l2, completing theelectrical circuit. In this manner of operation the heating of theelectrode in the vicinity of 7 is very little, and substantially only1by conduction, and

where I provide heat radiators 9, this conducted heat from 5 towards 7.is largely diverted into the surrounding air.

In any case, it will be appreciated that electrode 5, for instance, isunder operation with the external surface of the electrodev of theinternal surfaces of the electrodes 5 and 12, particularly that surfacesubject to electrical discharge. This phase of myresent invention is sofully covered in the eretofore mentioned co-pending applications of theapplicant that its function with reference to the present invention willbe better understood by those skilled in the art by reference to theaforesaid applications.

Having described one em iment of my invention,'I claim: p

1. A gaseous ionization electrical discharge device comprising atranslucent tube with a spaced extension end and a hollow metallicelectrode of relatively large area surrounding said tube end and sealedexternally to a small 'area `thereof to provide' a substantial spacingbetween the greater portion of the area ofsaid tube end and saidsurrounding electrode, said electrode being operated internally atsub-atmospheric pressure and externally at atmospheric pressure.

2. A gaseous luminous discharge device comprising a translucent tubecontaining a rarefied gas, and an electrode having two small annularportions of its internal surface in contact with said tube, one of saidannular portions being sealed to said tube, and the entire exterralsurfacev of said electrode being exposed to the airA surrounding thesaid device, whereby the heat generated in the said electrode, underoperation, is permitted to radiate into the said surrounding air bydirect contact with said air.

3. A gaseous ionization `electrical discharge device comprising atranslucent tube containing a rarefied gas and 'a hollow electrodemounted upon one end of said tube and supportedthereby by two smallannular portions of the internal surface of said electrode.

end containing a rarefied gas and provided with electrodes enclosing theends of said tube, said electrodes having a very small portion of theirinternal surface in contact with the external surface vof said tube endto provide a spacing between the remaining internal surface of saidelectrodes and the remaining external surface of the adjacent tube end.

5. In a luminous discharge device comprising a translucent tube withopen ends, containing a raretied gas and provided vwith electrodesenclosing the ends of said tubing, said electrodes having only two smallannular portions of their internal surface in direct contact with saidtranslucent tube and the entire external thereof exposed to theatmosphere, and a heat radiator mounted on the external surface of thesaid electrodes.

6. In a luminous discharge device comelectrode.

' MONTFORD MORRISON.

